Not calculating enough miles

[Rlhephner]

As I walk on a treadmill, I know how many miles I walk. I use my Fitbit for my fitness pal, but I no longer get accurate information. It is typically off by about 2 miles. When I am done with a 7 mile walk my Versa will show 5 miles, not even 15,000 steps. And that's almost 2 hours of walking. I start at 3.7 mph and ramp up to 4mph. Is this fixable or a glitch in your system?

[JohnnyRow]

On treadmill, distance = number of steps time stride length.

So 2 possible problem areas, steps and stride length

Steps - do you hold hand rails at all?  If so steps are probably not detected when the fitbit wrist is held steady.  You could put in pocket and get better step count but lose heart rate data.

Stride length - If step count is good, your stride length is probably set too short.

See Can I change my stride length in my Fitbit account? 

Instead of measuring stride, if you know what the distance should be and what Fitbit is giving you, you can make an approximate adjustment from that.

For instance, if you know you walked 7 mile and Fitbit says 5 miles, multiply stride length by (7 / 5).